How to Test 12v Glow Plugs From Start to Finish (With Jump Leads & Wire) - The Complete Guide.

[@paulchalder1904]

Thanks, saved me £9.99 buying a multimeter 😂... Worked a treat, faulty glow plug identified 👍

[@doitup]

Hi, glad the video helped you out. It's great when people let me know. It makes the effort making the video all worthwhile... 😀👍

[@nishg9886]

Great video. Thank you 🎉

[@doitup]

Hi, thanks for letting me know... 😀👍

[@kan815k]

If glowplug is 5v and connect it directly 12v. What will happen to plug, burn out?

[@doitup]

Hi, there are more and more non 12v glow plugs being fitted now, (I presume it's because the electronics are getting a bit more fancy). As it's a 5v glow plug, I wouldn't test them directly from the battery with 12v, (the 5v will be supplied from the glow plug control unit). What I would do, is test them as shown at: kzbin.info/www/bejne/j5yupJWIfa2BiZo (Test No.3 at position 7:19). This is where you can test the glow plugs when removed, but plugged into their connector, (so you can see if they glow & test the length of the timer operation). Don't heat them too many times, as they could overheat whilst out of the engine. Hope this helps... 😃

[@adrianlawrence4807]

Really helpful. tHanKs!

[@doitup]

Hi, I'm glad it helped you out. Thanks for letting me know... 😃

[@bexhill8777]

Simple&2point. Nice

[@doitup]

Hi, thanks for your comment. It's much appreciated... 😃

[@damn_pal_9311]

thx for the indepth testing

[@doitup]

No problem, I'm glad it was useful. Thanks for letting me know... 😃

[@thegreatawakening7945]

Do you disconnect battery when testing????

[@doitup]

Hi, there's no need to disconnect the battery. Just make sure the ignition is switched off. There are some tests where the ignition will need to be switched on, for example at: kzbin.info/www/bejne/j5yupJWIfa2BiZo. It should be noted that it's always best to keep the ignition switched off when not in use. Hope this helps... 😃

[@thegreatawakening7945]

@@doitup thanks so much for the quick response and information ive an old mitsubishi L300 van 1992

[@doitup]

No problem.... Great van, nice to see something like that still on the road... 👍

[@thegreatawakening7945]

@@doitup Thanks yours too what year is yours? If they made cars and vans like this now manufacturers would be out of business lol

[@doitup]

Hi, I don't have an L300, but I do have a 1960 Series II Land Rover. Not running though! 😒

[@shtic00]

Hi, I have a doubt that my glow plugs don't activate. They're good, new, but glow plug light on my dashboard never activates. Glow plug control module is ok (tried with new one and no change). My idea is to pull out a glow plug, leave it connected to car connector, ground it and give contact in my car to see if the glow plug is activated by the car. Is this dangerous to do? Also do you have an idea what could be wrong if they don't activate? Fuses in the engine bay are all good, battery is new, alternator is working properly.

[@doitup]

Hi, the glow plug light on the dashboard is never a good indication that they're working/not working, so cannot be relied upon in many cases. It's a great idea to test the glow plug whilst removed, if it's connected to its original connector. My video shoes what you need to do here: kzbin.info/www/bejne/j5yupJWIfa2BiZo. - Once removed, connect the glow plug to its connector. - Use a jump lead to ground the glow plug. - Make sure the glow plug isn't near anything that can burn or catch fire. - Switch on the ignition and see if the glow plug glows? - You can also check to see how long the glow plug activates for (by timing how long it glows). This method is much safer than testing a glow plug directly on the battery (as there is a danger of explosion from Hydrogen gas from the battery). The risk is low, but it can happen. Things to note: - Manufacturers won't recommend testing this way, because some types of glow plugs may burn out with prolonged use. So don't let the 'glow plug' glow for too long if the timer isn't working. - Some specialist, newer types of glow plugs (such as ceramic) may be a bit sensitive to testing this way. They can run on a different voltage to that of the battery, amongst other things... If nothing is working, (with new glow plugs, and a new control module), then it could be a bad earth, or connection somewhere. - With the power off. Try unplugging and plugging things back in again, in case there is a bad connection somewhere. And then test to see if it works? - With the power on and everything connected (don't touch anything live). Waggle, move cables and connectors around (don't disconnect anything) in case there is a broken wire? And then test to see if it works? After this, you may need someone with a test meter? Unfortunately, it's difficult to diagnose from afar (and each vehicle may be different). But it sounds like you're testing everything you can. Think logically, and go through everything step by step. It's sometimes worth making a rough drawing of the process, to confirm you're checking each step. Let us know how you get on, as it may help others? I hope this helps you, and you get it fixed... 😃

[@shtic00]

@@doitup Thanks for the detailed reply. I'll test if they glow as soon as it stops raining here. While i wait, i have some other questions. Is the glow plug control module activated or has anything to do with BCM in the cabin? I have some other strange behavior with parking sensors/car radio/connection to CAN module through obd port, that made me doubt that it may be misbehaving. My glow plug light used to work before. Once i did "reset self learned functions" through multiecuscan software, it was gone. Everything else the car has "relearned" but this was gone for good. I have 2012 Fiat Punto 1.3 multijet.

[@doitup]

Hi, modern electronics on vehicle's (approx post 2020) can be a real pain. Great when they work, but when it goes wrong! The glow plugs may be linked to a control module somewhere, (most things are now)? Fuse panels (in vehicles) can be controlled by an ECU, that shuts down a circuit(s) if a fault occurs? If you have other electrics doing strange things, then it could be a control unit misbehaving somewhere? A bit like the boot latch on my wife's mini that sometimes opens when you open the drivers door. Electronics and water... Grrrrrrr! Unfortunately, I've not touched a Fiat, so I can't help much there..? 😃

[@doitup]

Hang on... Reference my last comment. The engine in the video is in a Vauxhall. And is also fitted to Fiats, Opels & Fords! So I have inadvertently worked on a Fiat! 😅

[@shtic00]

@@doitup ...and Suzukis :) The rain stopped and i looked into it a bit. Couldnt remove the glow plug to check what i wanted. Instead i used multimeter to check rise in voltage on glow plug connector. When i give contact, it goes to about 3 volts on it and on control module itself. I think it should be 12 volts or more? Outer temperature is around 12 °C, car was not turned on since yesterday so the engine should be the same temperature. All the fuses checked and they are ok. All relays give resistance around 50-70 ohms between + and -

[@MrBestEditing]

Hi I’ve got a Ford Transit Custom Basically it’s a hard start when engine is cold and once it’s driven n warm it starts as many time as I would want Does this indicate glow plugs ? Refer Back Regards

[@doitup]

Hi, it sounds like it is. But, there is always a chance it could be something else? There could be other issues, such as the battery on the way out, faulty wiring, etc. All you can do is try and test for any of the potential issues, or replace parts one by one and see. Hopefully the video gives you a few things you can check, to see if the glow plugs are OK. Hope this helps... 😃

[@warryckscown5620]

@@doitup Best to diagnose the fault, and remedy those.. this is an old post nonetheless ..

[@rattlebob8984]

When touching a wire from positive terminal to the top of the glow plugs I get a massive spark as if the wire is touching ground. No idea why.

[@doitup]

Hi, it sounds like it's as you describe... The electrical path through the glow plug could be going straight to ground, (a dead short, no resistance... Make sure you are only touching the very end of the glow plug). It maybe worth checking to see if the glow plug is actually a 12v glow plug, by checking the manufacturer's data sheets online (just to make sure). As more modern vehicles can use different voltages. If you don't have a test meter, check to see if the glow plug works? If you have some jump leads, use 'Method 3' at kzbin.info/www/bejne/j5yupJWIfa2BiZo in the video. Don't heat the glow plug up too many times (whilst not fitted, as the glow plug could overheat). Be careful to avoid anything that can melt! 🔥🚒 Hope this helps and you get it fixed soon... 😃

[@rattlebob8984]

@@doitup Hi thanks for the reply. The funny thing is I did the test a few days ago and just got a small spark as expected. I found one dead plug so put in a new one. The only other thing I have done is charge the battery. Now I get the big spark as said, but also no voltage at the plugs when turning on the ignition. I expect either the relay or fuse needs replacing, I'll investigate further tomorrow . Whether the battery charger fried it somehow I don't know.

[@rattlebob8984]

The insulator on one of the plugs had failed and was shorting out, which blew the 80 amp fuse.

[@doitup]

Hi, glad you found the issue. Thanks for letting me know, as it's always useful to hear what the issue was, and how you managed to find it. There's often some satisfaction in finding out what the actual problem is and being able to fix it! 👍😃

[@leep381]

Hi, thanks for these video, they're really informative 👍🏻 Can I start my engine when testing like this (option 3) to see if the glow plugs cut out? Assuming they're working. I have tested the V at plug connectors and I'm getting 9.98v with key in position 2. When hold the probes on until the voltage cuts out, after more than 1min it doesn't cut out, 9.98v constant. This makes me think there might be a problem with the timer and burning out the glow plugs possibly. When I test the continuity of the plugs I get the beep on the multimeter, but testing the resistance doesn't give any reading, only none of the plugs, which makes me think they're all shot. I'm going to try the wire/spark test first tomorrow and if nothing I want to try removing one to test. But am also wondering, as this is a volvo c30 diesel, that maybe the plug voltage is only cut once the car is turned over. I know it's recommend to not start a diesel immediately, even though I do, but now see the logic why, to let the plugs warm up. I have a Reduced engine Performance message and my fault finding mission lead me to the glow plugs and/or GP circuit, but I dont have any or the usual symptoms I.e. difficult to start when cold, white smoke, noisy idling. The car fires up and runs fine whatever the weather. Thanks again for the videos. And what's the worst that can happen if I start the car with plugs connected but out the engine? TIA

[@doitup]

Hi, I'll try and answer your queries... - Starting the engine - The compression will be lower, if you have the glow plugs removed. There is a danger from fuel/air/exhaust being blown out the injector holes, (eye injury, and forced entry of combustion mixture through bare skin). - The voltage supply - is usually around 12v (for 12v systems). However, there are now more and more glow plugs using different voltages. With most glow plugs, you can check the voltage required using the manufacturers data sheets online. - Glow plug timer - Generally, the glow plug timer will operate with just the ignition on. The glow plugs timer should switch off the glow plugs at some point? But with electronics, you could have all sorts of fancy controls. So dependant on the vehicle and age (newer vehicles)... If you have a test meter, you can leave the glow plugs fitted. Just unplug the glow plug connector and check the voltage supply at the connector, and how long it's provided for. You can do this one glow plug at a time, (with just the ignition on, or the engine running). - Resistance - Before you start, you may need to check your test meters resistance? Select ohms, and connect the multimeters leads together. Is the meter reading 0 ohms? If not, recalibrate your test meter. If there is no facility to do this, just subtract the reading you obtained (when connecting the leads together) from the actual reading taken from the glow plugs. For example. If you get a glow plug reading of 14 ohms and your multimeter had a reading of 8 ohms, we now know the glow plug measured 6 ohms (14 ohms - 8 ohms = 6 ohms). Make sure the contact points (where you measure the glow plugs) are clean and free from oil and corrosion. - No test meter? - A good indicator on the state of the glow plugs would be to check if they glow (as per the video). - Modern vehicle electronics - Unfortunately, electronics can throw up all sorts of errors. Sometimes the electronics will indicate the correct fault... Yey! Sometimes electronics will indicate a fault that can't be found? It then turns out to be a bad connection somewhere on one of the many control units! Had that recently on a Mini. Dynamic stability brake system errors. Checked all the sensors, and associated parts, couldn't clear the error. In the end it was a tarnished pin on a connector on one of the control units. - Glow plugs failing under load - To check this, you need to measure the current supplied to the glow plugs and see if the current supply falls away. You can do this with a test meter, or a clamp meter. - Hopefully you've also seen: How to Test Glow Plugs From Start to Finish (With a Multimeter) - The Complete Guide: kzbin.info/www/bejne/pHfVp62pqaukrac. - More info can be found here: do-it-up.com/vehicles/engine-transmission/diesel-wont-start-when-cold-how-to-fix-glow-plugs/ Hope some of this helps you... 😃

[@leep381]

@@doitup Thanks for the reply... well I wont be turning the car over with the plugs out then, I am quite fond of my eyes, and not a fan of burnt skin lol. Thanks for the heads up! But I will re-connect everything bar one GP connector and test the voltage when the engine is started to see if it drops off at any point. I am 99.9999% sure all the plugs are dead. I tried the wire test today, from + battery terminal to the glow plug, but nothing, no sparks at all. I checked all fuses and relays and module for continuity as well and all OK. Testing continuity of the GP again, properly, with the black probe on the engine block near the plugs I found there was no beep, so Im pretty convinced they are all dead. Why, I am not sure yet. But my next step is to attempt to remove them, test, and replace, to see if that sorts it and how long they last before/if it happens again. Soaked the in some lubricant earlier, and will do that a few times to hope they dont end up snapping inside... fingers crossed. If I manage to replace them successfully, and it ends up happening again, I will try the current test (or is the current test related to what I was referring as the GP timer cutout/drop off?) Ye I've been though all your videos, very helpful thanks. Oh, also I did test my meter last night on a plug fuse and it seemed to be working fine. The plugs are just dead I think. I think the wire test today confirmed it.

[@doitup]

Hi, here's some tips on removing the glow plugs: do-it-up.com/vehicles/videos/engine-and-transmission/glow-plugs/how-to-remove-and-where-are-they-fitted/. See the web page text, as there is some additional info... (the video needs to be updated to include this additional text...). Sounds like you're on your way to getting it sorted... 😃

[@warryckscown5620]

you have smoke rising from the left side of ur engine as sooon as it fires up..

[@doitup]

Hi, well spotted! The injector copper washer is not sealing properly... I ignored this at my peril. I needed to remove the injectors some months later. It took 5 days (of going away in despair, and coming back to try again) before I got them (it) out! Carbon deposits had formed around the injector fixing it in solidly in place. Moral of the story: 1 - If you take the injectors out, always clean them and replace the copper washers. 2 - See a puff of smoke? Replace the copper washers at the earliest opportunity. 3 - You could walk away and hope you never have to take the injectors out! 4 - You may then have wished you'd changed them earlier! In my case the following order applied... 3, 4... then 1 with a lot of grief! You live and lean..! 😥

[@warryckscown5620]

@@doitup Well its not something you will normally see from the drivers seat.. happy to spot it for ya,, algud.

[@vinczejani]

this is how you can damage a 4.4V glow plug.

[@doitup]

Hi, yes. The video is nearly 5 years old now and was based on an older vehicle. Since then, more and more vehicles have switched to a 5 to 7 volt glow plug system... Unfortunately, to update a video, you have to start all over again from scratch. I have added 12V in the title and there is a note about the voltages in the text below the video "Typical values (next gen) 4.4v to 7v. The resistance value may also be below 1 ohms. You may need to refer to the manufacturers specifications, to get the correct value…" As a footnote, I would also check the glow plug manufacturer's data sheet online (for the glow plug fitment), as there are so many different voltages and resistance's used on vehicles now. Everything has moved up a notch, and is just a little more complicated now! Thanks for the prompt... 😃👍

[@vinczejani]

@doitup nice explanation. I appreciate your nice comment

[@doitup]

Hi, no problem. If you make a video that may help others, it's always useful to have the right info (as much as you can). Thanks for your positive reply... 😀